This invention pertains to a locking system utilizing expendable lock mandrels, which sealingly engage and releasably lock in landing nipples in well tubing to control flow through the tubing.
A number of types of expendable devices have been developed for use in landing nipples in well tubing for flow control purposes. One of these devices, an expendable standing valve, is currently available and is shown on page 266 of "General Sales Catalog" (OEC 5338), a publication of Otis Engineering Corporation, P. O. Box 819052, Dallas, Tex. 75381-9052. This standing valve seals and releasably locks in a landing nipple and permits upward flow and prevents downward flow through the valve.
U.S. Pat. No. 4,355,686 for WELL SYSTEM AND METHOD covers the use of expendable fluid control means, such as standing valves, in landing nipples in two tubing strings in an injection well. Another U.S. Pat. No. 4,360,063 for VALVE covers an expendable standing valve type flow control which is expended from a nipple by two applications of pressure. U.S. Pat. No. 4,718,488, discloses a pump-out plug which may be seated in a landing nipple having a landing sub in a well conduit. This plug may be closed, preventing flow through in both directions and the plug and landing sub may be expelled by pressure.
Yet another U.S. Pat. No. 3,250,331 for LOCKING DEVICE FOR WELL TOOLS discloses a locking device utilizing an expandable locking member in the form of a coil spring or split ring for releasably locking this device in a landing nipple in a flow conductor. This locking device when sealed and releasably locked in a landing nipple essentially "plugs" the landing nipple by preventing upward flow and permitting very small volume downward flow through an internal equalizing valve. This locking device cannot be expended downwardly from its landing nipple.